Specifies the validation strategy H2O LLM Studio uses for the experiment.

To properly assess the performance of your trained models, it is common practice to evaluate it on separate holdout data that the model has not seen during training. H2O LLM Studio allows you to specify different strategies for this task fitting your needs.

Options
- **Custom holdout validation**
    - Specifies a separate holdout dataframe.
- **Automatic holdout validation**
    - Allows to specify a holdout validation sample size that is automatically generated.